This project is an investigation of the role of complement in Dengue hemorrhagic shock. Clq reactive material, a potential activator of complement present in sera of Dengue patients, will be purified with the aid of a new radioimmunoassay and will be characterized immunochemically. Dengue virus infected lymphoblastoid cell cultures will serve as an vitro model for Dengue virus replication. Serum enzyme inhibitors will be measured in sera of Dengue patients with the radial immunodiffusion test.